Evaluation of the crossability between small grains

Date
2011-12
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: The greatest concern associated with genetically engineered crops is the possibility of GM crops contaminating other non-GM crops as a result of cross-pollination. Pollen drift is the primary mechanism in which GM crops contaminate traditional crops. However, genes can only be transferred between species if a certain degree of crossability exists. The aim of this study was to determine the potential risks associated with the release of transgenic crops and how to minimize these risks. Therefore, in this study crossability between three small grains was evaluated as well as pollen mediated gene flow from blue aleurone wheat. The potential frequency of cross pollination as well as the distance at which gene flow takes place was determined. When crossing triticale and rye the outcrossing was low in both directions. When rye was used as the female the F1 hybrid emergence was equal to zero and when triticale was used as the female parent the F1 hybrids were sterile. Therefore the potential for gene flow between triticale and rye is highly unlikely. The crossability between triticale and wheat was higher when triticale was used as the male parent, however these crosses did not produce many viable hybrid plants. When wheat was used as the male parent the F1 hybrid emergence was much higher and the F1 generation produced viable seed. In crosses between wheat and rye, gene flow is only possible when wheat acts as the female parent. The F1 generation is also capable of producing seed. In the pollen dispersal study an average OC of 0.4% was observed. A maximum OC of 2.4% was observed at a distance of 2.5 meters from the pollinator. There were samples with outcrossing percentages of 1% and 1.3% at distances of 50 meters and 60 meters respectively. Therefore, results indicated that prevailing wind direction is not necessarily associated with higher OC rates. Therefore, to reduce gene flow as much as possible an isolating distance of at least 65m should be used.
AFRIKAANSE OPSOMMING: Die grootste bekommernis geassosieer met geneties gemanipuleerde gewasse is die moonlikheid dat GM gewasse konvensionele gewasse kontamineer deur middel van kruisbestuiwing. Stuifmeel verspreiding is die primêre meganisme waardeur tradisionele gewasse met GMMgewasse gekontamineer word. Geenvloei tussen spesies kan egter net plaasvind as daar ‘n mate van kruisbaarheid bestaan tussen die gewasse. Die doel van hierdie studie was om die potensiële risiko’s verbonde aan die vrystelling van genetiese gewasse te bepaal asook hoe om hierdie risiko’s te verminder. Die kruisbaarheid tussen drie klein grane is bepaal asook die die stuifmeel bemiddelde geenvloei vanaf blou graan. Die potensiële frekwensie van kruisbestuiwing asook die afstand waarteen kruisbestuiwing kan plaasvind is ook bepaal. Wanneer korrog met rog gekruis word is die kruisbaarheid laag in albei rigtings. Wanneer rog as die vroulike ouer gebruik word, is die opkoms van die F1 generasie gelyk aan nul en wanneer korrog as die vroulike ouer gebruik word, is die F1 generasie steriel. Die potensiaal van geenvloei tussen rog en korrog is dus hoogs onwaarskynlik. Daar is bevind dat kruisbaarheid tussen korrog en koring hoër is wanneer korrog as die manlike ouer gebruik is. Hierdie kombinasie het egter nie baie lewensvatbare plante geproduseer nie. Wanneer koring gebruik word as die manlike ouer is die opkoms van die F1 generasie baie hoër en die F1 generasie produseer lewensvatbare saad. In kruisings tussen koring en rog is geenvloei slegs moontlik wanneer koring as die vroulike ouer gebruik word. Die F1 generasie is ook in staat om saad te produseer. In die stuifmeelverspreidingMstudie was ‘n gemiddelde kruisingsbaarheid persentasie van 0.4% waargeneem. ‘n Maximum kruisbaarheid persentasie van 2.4% was waargeneem teen ‘n afstand van 2.5m vanaf die stuifmeel donor. Daar was ook monsters wat 1% en 1.3% kruisbaarheid getoon het by afstande van 50 en 60 meter onderskeidelik. Resultate van die studie toon aan dat heersende winde nie noodwendig met hoër kruisbaarheid geassosieer word nie. Om geenvloei te verhoed, moet isolerende afstande van ten minste 65m gebruik word.
Description
Thesis (MScAgric)--Stellenbosch University, 2011.
Keywords
Triticale, Rye, Wheat, Outcrossing, Pollen mediated gene flow, Dissertations -- Genetics, Theses -- Genetics, Grain -- Breeding
Citation